Simultameous measurements of thoracic girth, headward
shift of center of gravity and functional residual
capacity of lung attending abrupt assumption of supine
position and sustained recumbency of 30 minutes period
in 8 adult male subjects were performed. The center
of gravity shifted 0.41 cmeO.25% body length) headward
after recumbency of 30 minutes. The thoracic
girth decreased a mean value of O. 82 em. The functio
nal residual capacity of lung showed a significant decrease
immediately after recumbency and was followed
by an insignificant decrease up to the end of 30 minutes
period. The interrelation between blood volume shift
to thorax, position of diaphragm. decrease in functional
residual capacity and decrease in the thoracic girth was
discussed.